Since Edison had used tungsten wire as the light emitting element of the bulb, the history of the traditional light bulb has been lasting for more than a hundred years. Because the incandescent light bulb is an omni-directional lighting and is safer than the candle or the kerosene lamp which might be easy to cause the disaster. Therefore, the incandescent light bulb is rapidly replacing the illumination device like the candle or the kerosene. However, the incandescent light bulb has low power efficiency so people are eager to find a more energy-efficient technology to replace the traditional incandescent light bulb.
The light-emitting diode (hereinafter referred to as LED) currently used in the light source of the illumination device is a higher efficient electronic component and in line with the trend of green energy. However, the light emitted from LED generally has directivity. Thus, although LED has the advantages of much low power consumption, LED lighting products and related design need further improvements to change the light pattern to meet the demand of omnidirectional lighting.
In addition, the LED can be further connected to other components in order to form a light-emitting apparatus including a sub-mount carrying an electrical circuit and a solder formed above the sub-mount.